<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .parent{
            width: 1000px;
            height: 100px;
            background: red;
            display: flex;
        }
        .parent>div{
            border: 1px solid #333;
            flex: 1;
        }
        .parent>.two{
            flex:2;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div>

        </div>
        <div class="two">
            
        </div>
        <div>
            
        </div>
        <div>
            
        </div>
    </div>
</body>
</html>